JP2000319462A - Polyolefin stretch packaging film - Google Patents

Abstract

(57) [Summary] (with correction) [Problem] To obtain a chlorine-free stretch film which is excellent in packaging workability and packaging finish, and excellent in temporal stability and economic efficiency. SOLUTION: The following component (A) is 40 to 80% by weight,
5 to 40% by weight of component (B) and 5 to 25 of component (C)
A polyolefin-based stretch packaging film comprising, as a main component, a resin composition consisting of 1% by weight and having at least one mixed resin layer having a heat of crystallization measured by a differential scanning calorimeter of 15 to 35 J / g. (A) a soft polypropylene resin having a controlled stereoregularity in which a crystalline block and an amorphous block portion are mixed in a molecular chain; and (B) a vinyl aromatic compound having a glass transition temperature of 0 ° C. or less. (C) Petroleum resin, terpene resin, coumarone-indene resin, rosin-based resin, or hydrogenated derivative thereof having a glass transition temperature of 50 to 100 ° C

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretch film suitably used for food packaging, and more particularly to a stretch packaging film made of a chlorine-free material.

[0002]

2. Description of the Related Art Conventionally, as a stretch packaging film for so-called prepackaging, in which fruits and vegetables, meat, side dishes, etc. are placed on a lightweight tray and overlapped with a film, a polyvinyl chloride-based film has been mainly used. . These have good packaging efficiency, good packaging finishes, etc., good packaging resilience, and excellent elastic recovery that returns to the original state even after applying deformation such as pressing the packed film with a finger, and good bottom sealability. This is because the merchandise and the consumer have the superiority of the quality that the value of the merchandise does not decrease such that the film is not easily peeled off during the transportation display.

[0003]

However, in recent years, problems such as hydrogen chloride gas generated during incineration of a polyvinyl chloride film and elution of a large amount of a plasticizer contained therein have been regarded as problems. For this reason, various alternatives to the polyvinyl chloride-based film have been studied, and in particular, various stretch packaging films using a polyolefin-based resin have been proposed. In recent years, ethylene-vinyl acetate copolymers have been used for the front and back layers, and various polypropylene-based resins have been used for the intermediate layer because of good surface properties and transparency as a stretch film, moderate heat resistance, freedom of material design, economy, etc. 2 kinds of ingredients 3
The study of a film for stretch packaging having a layer structure has been actively conducted.

[0004] However, the currently proposed stretch films containing various polypropylene-based resins as main components are mainly suitable for packaging such as packaging workability, packaging finish, elastic recovery force, bottom sealability (automatic machine, hand packaging). Comprehensive evaluations in the market, including economics, are still unsatisfactory.
The present inventors have previously proposed in Japanese Patent Application Laid-Open No. 9-154479 a food packaging stretch film containing a relatively low-crystalline propylene polymer and petroleum resins and having specific viscoelastic properties. ing.

The film comprising a propylene polymer and a petroleum resin described in the above publication has relatively good properties such as packaging workability, packaging finish, elastic recovery force and bottom sealability, but has a desired viscosity. In order to have elastic properties, a relatively large amount (30% by weight) of petroleum resins must be contained, so that the strength of the film changes over time, or the petroleum resins bleed to the surface, and the In such a case, there were problems such as blocking between the films.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a specific soft polypropylene-based resin composition is used as a main component, and its crystallinity and viscoelastic properties are controlled to improve packaging workability and packaging efficiency. It has succeeded in obtaining a non-PVC-based stretch film that has excellent properties such as finish, elastic recovery force, and bottom sealability, and also has excellent stability over time and economical efficiency. A) The component is 40 to 80% by weight, and the component (B) is 5 to 4%.
A resin composition comprising 0% by weight and 5 to 25% by weight of component (C) as a main component, and having at least one mixed resin layer having a heat of crystallization measured by a differential scanning calorimeter of 15 to 35 J / g. 10H frequency by dynamic viscoelasticity measurement
z, storage elastic modulus (E ') measured at a temperature of 20 ° C. is 5.0.
× 10 ⁸ dyn / cm ^{2 to} 5.0 × 10 ⁹ dyn / cm
^2. A polyolefin-based stretch packaging film, wherein the loss tangent (tan δ) is in the range of 0.2 to 0.8.

(A) A soft polypropylene resin having controlled stereoregularity in which a crystalline block and an amorphous block portion are mixed in a molecular chain satisfying the following conditions (1) to (3): (1) The sum of the fractions of mesopentad and racemopentad determined from the ¹³ C-NMR spectrum (mmmm + r
(rrr) is 30 to 75% (2) Using a differential scanning calorimeter at a heating rate of 10 ° C./min.
After the temperature was raised to 00 ° C and kept at 200 ° C for 5 minutes, the heat of crystallization measured when the temperature was lowered to room temperature at a cooling rate of 10 ° C / min was 10 to 60 J / g. (3) Melt flow rate (MFR) ( JISK721
0, 230 ° C, 2.16 kg load) is 0.4 to 40 g /
10 minutes (B) A copolymer of a vinyl aromatic compound having a glass transition temperature of 0 ° C. or less and a conjugated diene or a hydrogenated derivative thereof (C) Petroleum resin, terpene resin, and cumarone having a glass transition temperature of 50 to 100 ° C. -Indene resin, rosin resin, or hydrogenated derivative thereof

Further, as a flexible polypropylene resin having a controlled stereoregularity in which a crystalline block and an amorphous block portion are mixed in the molecular chain, 95% by mole of a propylene-based monomer unit is used. Contained, the mesopentad fraction (mmmm) is 25 to 65%, and the sum of the mesopentad fraction and the racemopentad fraction (mmmm + r
Resins having an rrr) in the range of 40 to 75% can be suitably used.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The stretch film of the present invention comprises the following component (A) in an amount of 40 to
80% by weight, 5 to 40% by weight of the component (B) and (C)
A resin composition comprising 5 to 25% by weight as a main component;
The heat of crystallization measured by a differential scanning calorimeter is 15 to 3
It has at least one mixed resin layer of 5 J / g, and has specific viscoelastic properties as a whole film. (A) Soft polypropylene resin with controlled stereoregularity in which a crystalline block and an amorphous block portion are mixed in a molecular chain satisfying the following conditions (1) to (3) (1) The sum of the fractions of mesopentad and racemopentad determined from the ¹³ C-NMR spectrum (mmmm + r
(rrr) is 30 to 75% (2) Using a differential scanning calorimeter at a heating rate of 10 ° C./min.
After the temperature was raised to 00 ° C and kept at 200 ° C for 5 minutes, the heat of crystallization measured when the temperature was lowered to room temperature at a cooling rate of 10 ° C / min was 10 to 60 J / g. (3) Melt flow rate (MFR) ( JISK721
0, 230 ° C, 2.16 kg load) is 0.4 to 40 g /
10 minutes (B) a copolymer of a vinyl aromatic compound having a glass transition temperature of 0 ° C. or less and a conjugated diene or a hydrogenated derivative thereof (C) a petroleum resin, a terpene resin, and a cumarone having a glass transition temperature of 50 to 100 ° C. -Indene resin, rosin resin, or hydrogenated derivative thereof

[0010] Here, the soft polypropylene resin as the component (A) generally has rubber elasticity, is soft and is not easily torn, since a crystalline block and an amorphous block portion are mixed in a molecular chain. It has the property of good transparency, and also has a crystalline block part having an isotactic structure and a syndiotactic structure exhibiting rigidity and an amorphous atactic structure exhibiting an elastomeric property present in the molecular chain. It is suitable to achieve the object of the present invention by balancing the ratio with the sexual block portion. A mixture of a crystalline block and an amorphous block in a molecular chain means that the crystalline block and the amorphous block are present randomly and / or in blocks. Although the chain length of each block portion may be arbitrary, it is preferable in the present invention that the distribution is random in terms of transparency, appearance, and the like.

Polypropylene resins are generally high in crystallinity and high in strength, and are relatively high in melting point and good in heat resistance among polyolefin resins, but they require a large force during extension due to their high crystallinity. It shows only non-uniform elongation and these properties remain in the mixture. Therefore, in the present invention, in order to obtain a film having good elongation, it is preferable to use a polypropylene resin having relatively low crystallinity. Conventionally, as this type of polypropylene resin, a large amount of ethylene or an α-olefin having about 4 to 12 carbon atoms was contained in propylene in a form such as copolymerization in order to impart low-temperature properties and flexibility at ordinary temperature. These are often used, and are also partially used for films, but these alone are not viscoelastically suitable for the present invention. That is,
Since this kind of resin conventionally used usually contains a large amount of α-olefin in propylene, its glass transition temperature is the glass transition temperature inherent in polypropylene (−).
(Approximately 10 ° C.), and the loss tangent (tan δ) to be described later is extremely small at less than 0.1 at room temperature.

The component (A) applied to the present invention is capable of satisfying the viscoelastic properties described below, and mainly controls the stereoregularity to reduce the crystallinity and increase the glass transition temperature of polypropylene. Original glass transition temperature (-1
(About 0 ° C.), thereby increasing tan δ at normal temperature. The sum of the meso pentad fraction specifically determined from ¹³ C-NMR spectrum under the condition (1) and Rasemopentaddo fraction (mmm
m + rrrr) is 30 to 75%, preferably the mesopentad fraction (mmmm) is 25 to 65%, and the sum of the mesopentad fraction and the racemopentad fraction (mmmm + r)
(rrr) of 40 to 75% is used. Here, if the above (mmmm + rrrr) is less than 30%, the crystallinity is too low and the film-forming property is extremely poor, and at room temperature, the film is too soft or lacks in strength, which poses a practical problem. Further, the raw material itself is easily blocked, which is not preferable in terms of handling properties. On the other hand, if it exceeds 75%, the loss tangent (tan δ) at room temperature, which is the object of the present invention, becomes difficult to fall within a desired range, which is not preferable. In addition, a large force is required at the time of film extension, and it shows only non-uniform elongation,
Not suitable for stretch film.

The values of the mesopentad fraction (mmmm) and the racemopentad fraction (rrrr) used in the present invention are calculated based on the measurement results of ¹³ C-NMR (nuclear magnetic resonance) spectrum. That is, a ¹³ C-NMR spectrum was measured and determined from a signal intensity ratio of each splitting peak (mmmm to mrrm) appearing in a 22.5 ppm to 19.5 ppm region due to a difference in chemical shift due to stereoregularity of a methyl group. The mmmm (mesopentad fraction) refers to a three-dimensional structure in which all five methyl groups that are side chains are located in the same direction with respect to a main chain formed by carbon-carbon bonds composed of any five consecutive propylene units. Rrrr (racemopentad fraction) refers to the structure or the ratio thereof, and rrrr (racemopentad fraction) means that five methyl groups as side chains alternate with a main chain formed by carbon-carbon bonds composed of any five consecutive propylene units. Means the three-dimensional structure located in the opposite direction or the ratio thereof. The assignment of the signal in the methyl group region is described in A. Zambelli et al
(Macromolecules 8 , 687, (197
5))

As condition (2), the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min using a differential scanning calorimeter,
After holding at 5 ° C. for 5 minutes, the heat of crystallization measured when the temperature was lowered to room temperature at a cooling rate of 10 ° C./min was 10 to 60 J /
g, preferably in the range of 20 to 60 J / g. If the heat of crystallization is less than 10 J / g, the crystallinity is too low, resulting in extremely poor film-forming properties. At room temperature, the film is too soft, the cutability is reduced, and the strength is insufficient, which poses a practical problem. On the other hand, when the heat of crystallization exceeds 60 J / g, a large force is required at the time of film extension and only uneven elongation is exhibited, which is not suitable for a stretch film. Further, as a condition (3), a melt flow rate (MFR) (JISK
7210, 230 ° C, 2.16 kg load) 0.4-4
One having a range of 0 g / 10 min, preferably 1.0 to 20 g / 10 min is used. Melt flow rate is 0.4g /
If the time is less than 10 minutes, the viscosity of the polymer itself is too high to make extrusion molding difficult, and if it is more than 40 g / 10 minutes, the viscosity of the polymer itself is too low and the film-forming stability is lost, or the strength of the film itself is insufficient. There is a practical problem.

In such a soft polypropylene resin, the monomer unit based on propylene in the copolymer composition is at least 90 mol% or more, preferably 95 mol% or more, and is used in Soxhlet extraction with boiling n-heptane. Has an insoluble content of 60% by weight or less, preferably 2 to
In Soxhlet extraction with 55% by weight, cold xylene, the insoluble content is 95% by weight or less, preferably 50% by weight.
Those having a range of from 90 to 90% by weight are suitably used. Here, when the monomer unit based on propylene in the copolymer composition is less than 90 mol%, the heat resistance is lowered, and when the α-olefin is copolymerized, the glass transition temperature becomes the original glass transition temperature of polypropylene (− (Approximately 10 ° C.), the loss tangent (tan δ) at room temperature becomes extremely small, which is not preferable. In addition, as components other than propylene, ethylene or an α-olefin having about 4 to 12 carbon atoms, 4-methylpentene-1, a cyclic olefin,
Styrene and the like can be mentioned, and ethylene is most preferably used. Here, the insoluble content due to boiling n-heptane is 60%.
If the amount exceeds 95% by weight or the insoluble content due to cold xylene exceeds 95% by weight, the crystallinity is so high that the flexibility is reduced, and the loss tangent (tan) at ordinary temperature, which is the object of the present invention, is obtained.
δ) hardly falls within a desired range. The component (A) can be used as a mixture of two or more kinds as long as it meets the purpose of the present invention.

The process for producing a soft polypropylene resin suitable for the present invention is carried out by using an inexpensive propylene monomer as a main component, various metallocene catalysts (single-site catalysts), solid titanium catalysts and the like. A method of polymerizing a flexible polypropylene resin with good stereoregularity controlled efficiently and at low cost has been proposed,
The resin to be used is not particularly limited as long as it satisfies the gist of the present invention.
ntsman Polymer Corporation
n of the product name “REXflex”.

Next, the component (B) has a glass transition temperature of 0 ° C.
The following is a copolymer of a vinyl aromatic compound and a conjugated diene or a hydrogenated derivative thereof. Such a copolymer generally has rubber elasticity, is soft and resistant to tearing, and has good transparency. Particularly, the hydrogenated derivative thereof has a good phase with the component (A). Shows solubility,
It effectively acts to impart flexibility at a low temperature to the mixed resin layer, expand a temperature region where tan δ shows a high value, improve transparency, and the like.
However, the glass transition temperature is 0 ° C. or less, preferably −20 ° C.
Must be: When the glass transition temperature exceeds 0 ° C., the effect of adding the component (B), such as imparting flexibility to the mixed resin layer at a low temperature, becomes insufficient. Further, the ratio between the vinyl aromatic compound and the conjugated diene of such a copolymer is preferably from 3/97 to 40/60 by weight.
Here, 3% by weight of the vinyl aromatic compound in the copolymer composition
When the molecular weight is less than 40, the rigidity of the copolymer itself is excessively reduced, and the polymerization productivity such as pelletization becomes difficult.
If the amount exceeds 10% by weight, the rigidity of the copolymer itself increases,
The effect of (B) the purpose of adding the component, such as imparting flexibility to the mixed resin layer at a low temperature, tends to be insufficient.

Here, as the vinyl aromatic compound,
Styrene is typical, but styrene homologues such as α-methylstyrene may also be used. Examples of the conjugated diene include 1,3-butadiene, isoprene, and 1,3-pentadiene, and these can be used alone or as a mixture of two or more. Further, as the third component, a small amount of a component other than the vinyl aromatic compound and the conjugated diene may be contained. However, when a double bond mainly composed of a vinyl bond in the conjugated diene portion remains, thermal stability and weather resistance are extremely poor. To improve this, 80% or more, preferably 95% of the double bond is improved. It is preferable to use one to which hydrogen is added as described above. Examples of such a copolymer include a styrene-butadiene block copolymer elastomer (trade name “TAFPRENE” by Asahi Kasei Kogyo Co., Ltd.),
Hydrogenated derivatives of styrene-butadiene block copolymers (Asahi Kasei Kogyo Co., Ltd., trade name "ToughTech", Shell Japan Co., Ltd., trade name "Clayton G"), hydrogenated derivatives of styrene-butadiene random copolymer (JSR
(Trade name "Dinalon"), hydrogenated derivatives of styrene-isoprene block copolymer (Kuraray Corp. name "Septon"), styrene-vinyl isoprene block copolymer elastomer (Kuraray trade name) These copolymers can be used alone or in admixture of two or more.

Among these, a hydrogenated derivative of a styrene / conjugated diene random copolymer having a styrene content of 5 to 25% by weight and a vinyl bond content of the conjugated diene portion exceeding 60%, preferably 65 to 90%, is used. It is particularly preferable from the viewpoint of improving compatibility with components (A) and (C), transparency, and imparting flexibility at low temperatures. The details of the hydrogenated derivative of the styrene / conjugated diene-based random copolymer which can be suitably used in the present invention and the production method thereof are described in JP-A-2-158643 and JP-A-2-30581.
4 and JP-A-3-72512. Further, as a specific example of such a copolymer, a structure of hydrogenated styrene butadiene rubber is used.
A material called by the abbreviation of "R", which is commercially available under the trade name "DYNARON 1320P" by JSR Corporation.

The component (C) has a glass transition temperature of 50 to 1.
A petroleum resin, a terpene resin, a cumarone-indene resin, a rosin-based resin, or a hydrogenated derivative thereof at 00 ° C. Since the component (C) has a high glass transition temperature, the glass transition temperature of the mixture can be increased. This effectively acts to make the storage elastic modulus (E ′) exhibiting suitable extensibility as a stretch film at room temperature and the loss tangent (tan δ) exhibiting appropriate stress relaxation properties compatible. Examples of the petroleum resin, there are an aromatic petroleum resin from alicyclic petroleum resins and C ₉ components from cyclopentadiene or dimer thereof, terpene resins and terpene from The terpene resin β- pinene - phenolic resin But,
Examples of the rosin resin include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin or pentaerythritol. It is known that the component (C) exhibits relatively good compatibility when mixed with the components (A) and (B).
It is preferable to use a hydrogenated derivative in terms of color tone, thermal stability, and compatibility.

As the component (C), those having various glass transition temperatures mainly depending on the molecular weight can be obtained. However, those having a glass transition temperature of 50 to 100 ° C., preferably 70 to 90 ° C. are suitable for the present invention. belongs to. Glass transition temperature is 5
When the temperature is lower than 0 ° C., when mixed with the above-mentioned components (A) and (B), it is necessary to incorporate a large amount of the viscoelastic property in order to obtain desired viscoelastic properties. Tends to occur. Further, the mechanical strength of the film as a whole is insufficient, and the film is easily broken, which may cause a practical problem. On the other hand, when the glass transition temperature exceeds 100 ° C., the compatibility with the components (A) and (B) deteriorates, and the film bleeds over time on the film surface, and the blocking and the transparency may decrease. For the reasons described above, it is preferable that the content of the component (C) is small as long as the viscoelastic properties described below can be achieved. In this regard, since the polypropylene resin having a controlled stereoregularity applied to the present invention has a glass transition temperature of about −10 ° C. or higher, α-olefins and the like have been conventionally used in propylene which has been commonly used. Compared to a low-crystalline propylene-based resin contained in a large amount, even a small amount of the component (C) effectively acts to adjust the desired viscoelastic properties.

Next, the mixed resin layer is made of a soft polypropylene resin having a controlled stereoregularity, which is the component (A).
0 to 80% by weight, 5 to 40% by weight, preferably 10 to 30% by weight of a copolymer of a vinyl aromatic compound and a conjugated diene as the component (B) or a hydrogenated derivative thereof, and the component (C) Some petroleum resins, terpene resins, cumarone-
5-25% by weight, preferably 10-25% by weight of indene resin, rosin-based resin or hydrogenated derivative thereof
This is a layer mainly composed of a resin composition consisting of Here, if the content of the component (A) is less than 40% by weight and the content of the component (B) exceeds 40% by weight, the film becomes stiff at room temperature and becomes difficult to handle, and the strength and cuttability. Is liable to decrease, and the cost is undesirably high. If the content of the component (B) is less than 5% by weight, the effect of improving flexibility at low temperatures (around 0 ° C.) becomes insufficient, which is not preferable. When the content of the component (C) is less than 5% by weight, the self-adhesiveness of the film is inferior, the effect of increasing the glass transition temperature of the mixed resin layer is small, and desired viscoelastic properties are hardly obtained. On the other hand, if the content exceeds 25% by weight, problems such as a change in the strength of the film over time, and the bleeding of the petroleum resin on the surface, and in the case of a roll, are likely to cause problems such as blocking between the films.

The mixed resin layer may further include a polypropylene-based resin which does not belong to the definition of the component (A) in a range that does not impair the gist of the present invention, preferably in a range of 30% by weight or less of the mixed resin layer. One or more resins may be used in combination with the component (A) for the purpose of further improving the suitability for packaging such as film stiffness and cutability and the economic efficiency. However,
Also in this case, the heat of crystallization measured by a differential scanning calorimeter needs to be 15 to 35 J / g, preferably 20 to 35 J / g. Here, the heat of crystallization of the mixed resin layer is 15 J
If it is less than / g, the stiffness, cuttability and strength of the film will be reduced, and the heat resistance will be undesirably reduced. 35J
If it exceeds / g, the stiffness, cuttability and strength of the film are improved, but the restoring property of the finger impression is liable to decrease. It can be inferred that this is because, when the mixed resin layer has high crystallinity, the strain when undergoing large deformation is unevenly distributed in the film, and the strain tends to remain. The heat of crystallization used here was determined by raising the temperature of the resin composition constituting the mixed resin layer to 200 ° C. at a heating rate of 10 ° C./min using a differential scanning calorimeter.
It is the heat of crystallization measured when the temperature is lowered to room temperature at a cooling rate of 10 ° C./min after holding at 5 ° C. for 5 minutes.

Here, the polypropylene resin which does not belong to the definition of the component (A) is a homopolymer of propylene or a copolymer with another monomer copolymerizable with propylene. Other copolymerizable monomers include ethylene, butene-1, hexene-1, 4-methyl-pentene-
Examples thereof include α-olefins having 4 to 12 carbon atoms such as 1, octene-1, and dienes such as divinylbenzene, 1,4-cyclohexadiene, dicyclopentadiene, cyclooctadiene, and ethylidene norbornene. Of these, the use of ethylene is preferred. (A),
(B), propylene-ethylene random copolymer or propylene-ethylene-butene-1 copolymer is preferred from the viewpoint of transparency and packaging machine properties when mixed with the component (C),
For the purpose of improving low-temperature properties (especially low-temperature elongation), a low-crystalline polypropylene elastomer having a heat of crystallization of 50 J / g, preferably 40 J / g or less can be suitably used. As the low-crystalline polypropylene-based elastomer, a reactor-type polypropylene-based elastomer is preferable from the viewpoint of transparency and economy when mixed with the components (A), (B), and (C). ) Tokuyama's trade name “PER”, Chisso Corporation's trade name “NEWCON”, Montell-JPO trade name “Catalloy”, and the like.

Here, when the polypropylene resin not belonging to the definition of the component (A) is a copolymer of propylene and another monomer copolymerizable with propylene, the content of the other monomer is as follows. , Usually not more than 40% by weight, preferably not more than 30% by weight. These polypropylene resins can be used alone or in combination of two or more. Also, its melt flow rate (MFR) (JI
SK7210, 230 ° C, 2.16 kg load) is usually 0.4 to 20 g / 10 min, preferably 0.5 to 5 g / 1.
A time of 0 minutes is used.

Next, the film of the present invention has a storage elastic modulus (E ') of 5.0 × 10 ⁸ dyn / cm ^{2 to} 5.0 × 1 at a frequency of 10 Hz and a temperature of 20 ° C. by dynamic viscoelasticity measurement.
⁰⁹ dyn / cm ² , loss tangent (tan δ) is 0.2 to
It is in the range of 0.8. Here, tan δ (loss tangent) is the ratio of loss elastic modulus (E ″) to storage elastic modulus (E ′), that is, loss tangent (tan δ = E ″ /
E ′), which means that in a temperature range where this value is high, the loss elastic modulus (E ″) of the material, that is, the viscous contribution ratio of the viscoelastic properties is large. The evaluation of the temperature region showing the above is a large guide for judging the stress relaxation behavior and the like of the film in various packaging processes by hand packaging using a stretch film or an automatic machine.

The storage elastic modulus E 'is 5.0 × 10 ⁸ d
If it is less than yn / cm ^2, it is soft and the stress for deformation is too small, so that the workability is poor, the film of the pack product is not stretched, and it is not suitable as a stretch film. on the other hand,
When E ′ exceeds 5.0 × 10 ⁹ dyn / cm ² ,
The film becomes hard and hard to stretch, and the tray is easily deformed or crushed. A preferable range of E 'is 8.0 × 10 ⁸ dy.
n / cm ^{2 to} 3.0 × 10 ⁹ dyn / cm ² . Further, when tan δ is less than 0.2, since the restoration behavior with respect to the elongation of the film is instantaneous, the film is restored in a short time until the film is folded into the bottom of the tray, and the film does not stretch properly. Wrinkles are easy to occur. Also, in the heat sealing state of the bottom, in the case of stretch packaging, sufficient fusion by heat is difficult to be performed, so that the bottom seal is likely to be peeled off during transportation or display after packaging. Further, when tan δ exceeds 0.8, although the packaging finish is good, it shows plastic deformation,
Since the tension of the pack product against external force is too weak, the film on the upper surface of the tray easily sags due to stacking during transportation or display, and the commercial value tends to decrease. Further, in the case of automatic packaging, problems such as poor chucking are likely to occur because the packaging is easily stretched vertically. A particularly preferred range of tan δ is 0.30 to 0.1.
60.

Further, the stretch film is sometimes used at a low temperature, and it is desirable that the stretch film has excellent low-temperature characteristics (especially, elongation). For this purpose, the storage film measured at a frequency of 10 Hz and a temperature of 0 ° C. by dynamic viscoelasticity measurement is used. An elastic modulus (E ') of 1.5 × 10 ¹⁰ dyn / cm ² or less;
Preferably, it is 1.0 × 10 ¹⁰ dyn / cm ² or less. The frequency is 10H by dynamic viscoelasticity measurement.
z, loss tangent (tan δ) measured at a temperature of 0 ° C. is 0.1
It is preferably 0 or more, preferably 0.15 or more.
This is because, by expanding the temperature range having a high tan δ value in the room temperature region, the suitability for packaging under various use temperature environments is improved.

A flexible polypropylene resin mainly controlled in stereoregularity which conforms to the present invention is a conventional polypropylene resin containing a large amount of ethylene or an α-olefin having about 4 to 12 carbon atoms in the form of a copolymer or the like. Since the glass transition temperature is higher than that of the soft polypropylene-based resin, it is preferable to consider the properties of the viscoelasticity in order to secure flexibility such as low-temperature elongation. For this purpose, as described above, the proportion of the crystalline block portion such as the mesopentad fraction (mmmm) and the racemopentad fraction (rrrr), the type and the proportion of the component copolymerized with propylene, or (A), (B) , (C) The mixing ratio of each component may be adjusted.

According to the present invention, a stretch film composed of the above-described mixed resin layer is obtained. However, another non-chlorine-based material layer is laminated as a surface layer on at least one side, preferably both sides of the mixed resin layer. Is preferred. Other resin layers include non-chlorine-based material layers such as polyolefin-based resins and flexible styrene-butadiene-based elastomers. By laminating these layers, the viscoelastic properties of the film are adjusted and the processability of the film is improved. In addition, the appearance, flexibility and tensile properties are improved to provide moderate strength and elongation, and elongation at low temperatures is improved. Here, as the surface layer, a polyolefin-based resin is particularly preferable from the viewpoint of imparting surface characteristics and economy, and low-density polyethylene, linear ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer Use of (EVA), an ethylene-alkyl acrylate copolymer, an ethylene-alkyl methacrylate copolymer, an ethylene-acrylic acid copolymer, or the like is recommended.

In practice, EVA and / or a linear ethylene-α-olefin copolymer can be suitably used, and the mixing ratio can be determined appropriately. The EVA has a vinyl acetate content of 5 to 25% by weight,
Preferably 10 to 20% by weight, melt flow rate (M
FR (JISK7210, 190 ° C, 2.16 kg load) of 0.2 to 5 g / 10 min is suitable. Here, when the vinyl acetate content is less than 5% by weight, the obtained film is hard, the flexibility and the elastic recovery are reduced, and the surface tackiness is hardly developed. On the other hand, if it exceeds 25% by weight, the surface tackiness is too strong, and the unwinding property and appearance are liable to deteriorate. Also,
Examples of the linear ethylene-α-olefin copolymer include α
The olefin content is from 5 to 25% by weight, preferably from 10 to
15% by weight, MFR (JIS K7210, 190 ° C,
(2.16 kg load) of 0.2 to 5 g / 10 min is suitable. If the α-olefin content is less than 5% by weight, the resulting film is hard, and it is difficult to obtain uniform extensibility during stretch packaging. Therefore, wrinkles are generated in the package, and the package is easily crushed. If it exceeds, film forming becomes difficult or the unwinding property is liable to decrease. As the α-olefin, a butene having 4 to 8 carbon atoms is used.
1, hexene-1, 4-methyl-pentene-1 and octene-1 are preferred, and these can be used alone or in combination of two or more.

When the MFR of both EVA and the linear ethylene-α-olefin copolymer is less than 0.2 g / 10 minutes, the extrudability decreases, while when the MFR exceeds 5 g / 10 minutes, the film-forming stability decreases. It is not preferable because the thickness tends to decrease, and unevenness in thickness, a decrease in mechanical strength, and variations easily occur. In general, the thickness of the film of the present invention is in a range used for ordinary stretch packaging, that is, about 8 to 30 μm, typically about 10 to 20 μm. When a laminated film is used, the ratio of the thickness of the mixed resin layer to the total thickness is 0.3 to 0.9, preferably 0.4 to 0.9.
It is preferably from 0.8 to 0.8, and specifically from 5 to 20 μm, from the viewpoints of various properties as a stretch film and economy.

The film of the present invention can be obtained by melt-extruding a material from an extruder and forming the film by inflation molding or T-die molding. In the case of forming a laminated film, it is advantageous to co-extrude with a multilayer die using a plurality of extruders. Practically, it is preferable to melt-extrude the material resin from the annular die to perform inflation molding, and the blow-up ratio (bubble diameter / die diameter) at that time is preferably 4 or more, and particularly preferably in the range of 5 to 7. . As a cooling method at that time, either a method of cooling from the outer surface of the tube or a method of cooling from both the outer and inner surfaces of the tube may be used. Further, the film obtained here is heated to a temperature not higher than the crystallization temperature of the resin, and stretched 1.2 to 5 times in the machine direction of the film by utilizing the speed difference between the nip rolls, or 1. Biaxial stretching may be performed 2 to 5 times.

In the film of the present invention, the following various additives are appropriately added to the surface layer and / or the mixed resin layer in order to impart properties such as antifogging property, antistatic property, slipperiness and self-adhesiveness. can do. For example, when the carbon number is 1 to 1
2, preferably an aliphatic alcohol fatty acid ester which is a compound of an aliphatic alcohol having 1 to 6 and a fatty acid having 10 to 22 carbon atoms, preferably 12 to 18 carbon atoms, specifically, monoglycerin oleate, polyglycerin Oleate, glycerin triricinoleate, glycerin acetyl ricinoleate, polyglycerin stearate, polyglycerin laurate, methyl acetyl ricinoleate, ethyl acetyl ricinoleate, butyl acetyl ricinoleate, propylene glycol oleate, propylene glycol laurate, pentaerythritol oleate, Polyethylene glycol oleate, polypropylene glycol oleate, sorbitan oleate, sorbitan laurate, polyethylene glycol sorbitan oleate, polyethylene glycol sol Tanraureto like, as well as, polyalkylene ether polyols, specifically,
Polyethylene glycol, polypropylene glycol and the like, and further, at least one compound selected from paraffinic oils and the like, 0.1 to 12 parts by weight, preferably 1 to 12 parts by weight, based on 100 parts by weight of the resin component constituting each layer. It is preferable to mix 8 parts by weight.

[0035]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In addition, various measured values and evaluations of the film displayed in this specification were performed as follows. Here, the direction of taking out the film from the extruder (flow direction)
Is called the vertical direction, and the orthogonal direction is called the horizontal direction. (1) E ', tan δ Viscoelastic spectrometer VES- manufactured by Iwamoto Seisakusho Co., Ltd.
Using F3, vibration frequency 1
The temperature was measured from -50 ° C to 150 ° C at a rate of 1 ° C / min at 0 Hz, and values at temperatures of 20 ° C and 0 ° C were indicated from the obtained data.

(2) Suitability for stretch packaging Using a stretch film having a width of 350 mm, an automatic packaging machine (ISHIDA / WminMK-I manufactured by Ishida Koki Co., Ltd.)
I) foamed polystyrene tray (length 200mm,
130 mm in width and 30 mm in height) were packaged, and the items shown in Table 3 were evaluated. Using the same film and tray, a hand wrapping machine (Diawrapper A manufactured by Mitsubishi Plastics, Inc.)
-105) to conduct a packaging test.

(3) Glass transition temperature (Tg), melting temperature (Tm) Using a Perkin Elmer DSC-7, a 10 m sample was prepared.
g was determined from a thermogram when the temperature was increased at a heating rate of 10 ° C./min according to JIS K7121.

(4) Crystallization temperature (Tc), heat of crystallization (ΔHc) Using a DSC-7 manufactured by PerkinElmer, a 10 m sample was prepared.
g was heated to 200 ° C. at a heating rate of 10 ° C./min according to JIS K7121 and JIS K7122.
After holding for 1 minute, it was determined from a thermogram when the temperature was lowered to room temperature at a cooling rate of 10 ° C./minute.

(5) Melt flow rate (MFR) According to JIS K7210, unless otherwise specified, it was measured at a test temperature of 230 ° C. and a test load of 2.16 kgf.

(6) Mesopentad fraction (mmmm)
Rasemopentaddo fraction (rrrr) of Japan Electron Co., Ltd. JNM-GSX-270 ⁽¹³ C-
Nuclear magnetic resonance frequency of 67.8 MHz) under the following conditions
^{The 13} C-NMR spectrum was measured, and the difference in chemical shift due to the stereoregularity of the methyl group was 22.5 ppm.
分裂 19.5 ppm region, each splitting peak (mmmm
Ｍmrm). The assignment of the signal in the methyl group region is described in A.I. Zambelli
et al (Macromoleculees 8, 6
87, (1975)). Measurement mode: ¹ H-complete decoupling Pulse width: 8.6 microseconds Pulse repetition time: 30 seconds Total number of times: 7,200 times Solvent: mixed solvent of orthodichlorobenzene / deuterated benzene (80/20% by volume) Sample concentration: 100 mg / 1 ml solvent Measurement temperature: 130 ° C

(7) Time-dependent change The obtained film roll was heated at a temperature of 50 ° C. and a relative humidity of 60.
% For 10 days, and then evaluated the surface condition and the rewinding property. ◎: There is no bleeding of the additive on the surface and no blocking between films. …: There is almost no bleeding of the additive on the surface, but there is a little blocking between the films. Δ: There is little bleeding of the additive on the surface, and peeling is slightly heavy due to blocking between films. ×: There is much bleeding of the additive on the surface, and the blocking between the films is so severe that it cannot be used practically.

(Example 1) Component (A) Soft polypropylene resin having controlled stereoregularity (propylene content: 100 mol%, mmmm: 63.0%, rrrr: 8.0%, MFR: 2.0 g) / 10 min, Tm: 159 ° C., Huntsman Polymer Corporation, REXflexW105): 60% by weight (B) component Hydrogenated styrene-butadiene rubber (styrene content: 10%, vinyl bond amount in conjugated diene portion: 78%, Specific gravity: 0.89, MFR: 3.5 g / 10 min, Tg: −50 ° C., DYNARON1320P, manufactured by JSR Corporation): 20% by weight (C) component Hydrogenated derivative of cyclopentadiene-based petroleum resin (softening temperature: 125 ° C., glass transition temperature 81 ° C.): 20% by weight EVA (vinyl acetate content: 15% by weight, 190 ° C., MFR at 2.16 kg load: 11 μm thick)
2.0 g / 10 minutes) A three-layer annular die temperature of 100 parts by weight was melt-kneaded with 3.0 parts by weight of diglycerin monooleate as an antifogging agent so that each layer had a thickness of 2 μm.
Co-extrusion blown molding at 0 ° C. and a blow-up ratio of 5.5 gave a total thickness of 15 μm (2 μm / 11 μm / 2 μm).
m) was obtained.

The properties of the film consisting of the soft polypropylene resin alone as the component (A) were measured and the characteristics were as follows. The storage modulus at 0 ℃ (E ') 1.6 × 10 10 dyn / cm 2 0 loss tangent at ° C. (tan [delta) storage modulus at 0.17 20 ℃ (E') 3.7 × 10 9 dyn / cm ² Loss tangent (tan δ) at 20 ° C. 0.14 Peak temperature and value of loss tangent (tan δ) 8 ° C., 0.26 Glass transition temperature (Tg) −6 ° C. Heat of crystallization (ΔHc) 54 J / g Crystallization temperature (Tc) 108 ° C

The properties of the film composed of the above-mentioned three-component resin composition were as follows. Storage modulus at 0 ° C. (E ′) 1.1 × 10 ¹⁰ dyn / cm ² Loss tangent (tan δ) at 0 ° C. 0.21 Storage modulus at 20 ° C. (E ′) 1.8 × 10 ⁹ dyn / cm ² Loss tangent (tan δ) at 20 ° C. 0.38 Peak temperature and value of loss tangent (tan δ) 15 ° C., 0.40 Glass transition temperature (Tg) −7 ° C. Heat of crystallization 32 J / g Crystallization temperature (Tc) 103 ° C

Example 2 A film was obtained in the same manner as in Example 1, except that the total thickness was changed to 15 μm (4 μm / 7 μm / 4 μm).

(Example 3) In place of EVA used as the resin for the front and back layers in Example 1, linear ethylene-α was used.
-Olefin copolymer (α-olefin: octene-1
Content: 12% by weight, MFR at 190 ° C, 2.16 kg load: 1.0 g / 10 min, Tm: 102 ° C, AFFINITY PL188, manufactured by Dow Chemical Japan Co., Ltd.
0) except that total thickness 15
A film of μm (2 μm / 11 μm / 2 μm) was obtained.

Example 4 A soft polypropylene resin (II) was used in place of the soft polypropylene resin (I) having controlled stereoregularity used as the component (A) in Example 1
(Propylene content: 97 mol%, ethylene content: 3 mol%, mmmm: 32.1%, rrrr: 14.5%, M
FR: 6.0 g / 10 min, Tm: 150 ° C., Hunts
manufactured by man Polymer Corporation,
Using REXflex W210), the mixing ratio of the three resins was changed to 40% by weight of the component (A), 10% by weight of the component (B), and 20% by weight of the component (C). Mol%, MFR = 1.3 g / 10
A film having a total thickness of 15 μm (2 μm / 11 μm / 2 μm) was obtained in the same manner as in Example 1, except that a resin composition in which 30% by weight of Tm = 147 ° C.) was used as the mixed resin layer.

The properties of the film composed of the soft polypropylene resin (II) alone as the component (A) were measured and the characteristics were as follows. Storage modulus at 0 ° C. (E ′) 5.4 × 10 ⁹ dyn / cm ² Loss tangent (tan δ) at 0 ° C. 0.50 Storage modulus at 20 ° C. (E ′) 3.5 × 10 ⁸ dyn / cm ² Loss tangent (tan δ) at 20 ° C. 0.33 Peak temperature and value of loss tangent (tan δ) 7 ° C., 0.65 Glass transition temperature (Tg) −7 ° C. Heat of crystallization (ΔHc) 22 J / g Crystallization temperature (Tc) 92 ° C

The properties of the film composed of the mixed resin composition composed of the above four components were as follows. Storage modulus at 0 ° C. (E ′) 1.2 × 10 ¹⁰ dyn / cm ² Loss tangent (tan δ) at 0 ° C. 0.14 Storage modulus at 20 ° C. (E ′) 2.1 × 10 ⁹ dyn / cm ² Loss tangent (tan δ) at 20 ° C. 0.43 Peak temperature and value of loss tangent (tan δ) 20 ° C., 0.43 Glass transition temperature (Tg) −7 ° C. Heat of crystallization (ΔHc) 31 J / g Crystallization temperature (Tc) 96 ° C

Comparative Example 1 The procedure of Example 1 was repeated except that the mixing ratio of the three resins used in Example 1 was changed to 80% by weight of component (A), 0% by weight of component (B), and 20% by weight of component (C). Total thickness 15μm as in 1.
(2 μm / 11 μm / 2 μm) was obtained.

The properties of the film composed of the mixed resin composition of the components (A) and (C) were as follows. The storage modulus at 0 ℃ (E ') 2.2 × 10 10 dyn / cm 2 0 loss tangent at ° C. (tan [delta) storage modulus at 0.03 20 ℃ (E') 6.5 × 10 9 dyn / cm ² Loss tangent (tan δ) at 20 ° C. 0.26 Peak temperature and value of loss tangent (tan δ) 23 ° C., 0.28 Glass transition temperature (Tg) 6 ° C. Heat of crystallization (ΔHc) 44 J / g Crystallizing temperature ( Tc) 105 ° C

Comparative Example 2 A film was obtained in the same manner as in Example 1 except that the total thickness was changed to 15 μm (4 μm / 7 μm / 4 μm) in Comparative Example 1.

Comparative Example 3 Example 3 was repeated except that the mixing ratio of the three resins used in Example 1 was changed to 70% by weight of component (A), 30% by weight of component (B), and 0% by weight of component (C). Total thickness 15μm as in 1.
(2 μm / 11 μm / 2 μm) was obtained.

The properties of the film composed of the mixed resin composition of the components (A) and (B) were as follows. 0 storage modulus at ℃ (E ') 3.9 × 10 9 dyn / cm 2 0 loss tangent at ° C. (tan [delta) storage modulus at 0.29 20 ℃ (E') 1.3 × 10 9 dyn / cm ² Loss tangent (tan δ) at 20 ° C. 0.16 Peak temperature and value of loss tangent (tan δ) 1 ° C., 0.29 Glass transition temperature (Tg) −20 ° C. Heat of crystallization (ΔHc) 38 J / g Crystallization temperature (Tc) 109 ° C

(Comparative Example 4) Instead of the soft propylene resin (I) having controlled stereoregularity used as the component (A) in Example 1, low crystalline propylene-ethylene-
Propylene copolymer elastomer (propylene content: 8
8 mol%, ethylene content: 12 mol%, MFR = 1.5
g / 10 min, Tm = 156 ° C., manufactured by Tokuyama Corporation
“P.E.R.T310J” (hereinafter abbreviated as PER))
The total thickness was 15 μm in the same manner as in Example 1 except that the mixing ratio of the three resins was changed to 70% by weight of the component (A), 0% by weight of the component (B), and 30% by weight of the component (C).
(2 μm / 11 μm / 2 μm) was obtained.

The properties of the film composed of PER alone, which is the component (A), were as follows. The storage modulus at 0 ℃ (E ') 3.6 × 10 9 dyn / cm 2 0 loss tangent at ° C. (tan [delta) storage modulus at 0.14 20 ℃ (E') 2.1 × 10 9 dyn / cm ² Loss tangent (tan δ) at 20 ° C. 0.07 Peak temperature and value of loss tangent (tan δ) −10 ° C., 0.18 Glass transition temperature (Tg) −25 ° C. Heat of crystallization (ΔHc) 31 J / g Crystallization Temperature (Tc) 101 ° C

The properties of the film composed of the mixed resin composition of the components (A) and (C) were as follows. 0 storage modulus at ℃ (E ') 9.0 × 10 9 dyn / cm 2 0 loss tangent at ° C. (tan [delta) storage modulus at 0.19 20 ℃ (E') 2.0 × 10 9 dyn / cm ² Loss tangent (tan δ) at 20 ° C. 0.35 Peak temperature and value of loss tangent (tan δ) 20 ° C., 0.35 Glass transition temperature (Tg) −7 ° C. Heat of crystallization (ΔHc) 21 J / g Crystallization temperature (Tc) 100 ° C

Comparative Example 5 A commercially available polyvinyl chloride stretch film (thickness: 15 μm) was evaluated.
For the above Examples 1 to 4 and Comparative Examples 1 to 5, Table 1 shows the measured values of the viscoelastic properties of each laminated film (Comparative Example 4 was a single layer), and Table 2 shows the evaluation of stretch packaging suitability and the like. .

[Table 1]

[Table 2]

[Table 3]

From Tables 1 to 3, the films of Examples 1 to 4 having the three components specified by the present invention and having the viscoelastic properties within the range specified by the present invention all have various properties as stretch films. It turns out that it is excellent overall. On the other hand, it is understood that the films of Comparative Examples 1 to 4 having different components or having viscoelastic properties outside the range specified in the present invention are inferior in overall properties as a stretch film.

[0060]

According to the stretch film of the present invention, when used in an automatic wrapping machine, the film can be cut / transported and wrapped without any problem, the bottom sealing property is good, and the film tension is good. A package can be obtained, and it has a feature not found in the past as a chlorine-free stretch film. Furthermore, it has excellent stability over time and economic efficiency.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 45:02 93:04) F term (Reference) 4F071 AA12 AA14 AA20 AA22 AA78 AA80 AA86 AA88 AA89 AF20 AF43 AH04 BC01 4J002 AF023 BA013 BB121 BB141 BB151 BK003 BP012 BP021 FD100 FD340 GF00 GG02

Claims (6)

[Claims] (1) The following component (A) is 40 to 80% by weight,
5 to 40% by weight of component (B) and 5 to 25 of component (C)
At least one mixed resin layer mainly composed of a resin composition consisting of 1% by weight and having a heat of crystallization of 15 to 35 J / g as measured by a differential scanning calorimeter. The storage elastic modulus (E ') measured at 20 ° C. is from 5.0 × 10 ⁸ dyn / cm ^{2 to} 5.0 × 1.
⁰⁹ dyn / cm ² , loss tangent (tan δ) is 0.2 to
A polyolefin-based stretch packaging film, wherein the thickness is in the range of 0.8. (A) Soft polypropylene resin with controlled stereoregularity in which a crystalline block and an amorphous block portion are mixed in a molecular chain satisfying the following conditions (1) to (3) (1) The sum of the fractions of mesopentad and racemopentad determined from the ¹³ C-NMR spectrum (mmmm + r
(rrr) is 30 to 75% (2) Using a differential scanning calorimeter at a heating rate of 10 ° C./min.
After the temperature was raised to 00 ° C and kept at 200 ° C for 5 minutes, the heat of crystallization measured when the temperature was lowered to room temperature at a cooling rate of 10 ° C / min was 10 to 60 J / g. (3) Melt flow rate (MFR) ( JISK721
0, 230 ° C, 2.16 kg load) is 0.4 to 40 g /
10 minutes (B) a copolymer of a vinyl aromatic compound having a glass transition temperature of 0 ° C. or less and a conjugated diene or a hydrogenated derivative thereof (C) a petroleum resin, a terpene resin, and a cumarone having a glass transition temperature of 50 to 100 ° C. -Indene resin, rosin resin, or hydrogenated derivative thereof 2. A propylene-based soft polypropylene resin whose stereoregularity is controlled, in which (A) a crystalline block and an amorphous block portion are present in a molecular chain constituting a mixed resin layer. Containing 95 mol% or more of monomer units, and having a mesopentad fraction (mmmm) of 25 to 65%,
The polyolefin stretch packaging film according to claim 1, wherein the sum (mmmm + rrrr) of the mesopentad fraction and the racemopentad fraction is 40 to 75%. 3. The copolymer (B) comprising a vinyl aromatic compound and a conjugated diene or a hydrogenated derivative thereof, which constitutes the mixed resin layer, has a styrene content of 5 to 25% by weight and a vinyl bond of a conjugated diene portion. The polyolefin-based stretch packaging film according to claim 1 or 2, which is a hydrogenated derivative of a styrene / conjugated diene-based random copolymer having an amount exceeding 60%. 4. A polypropylene that does not belong to the definition of (A) a soft polypropylene resin having a controlled stereoregularity in which a crystalline block and an amorphous block portion are mixed in a molecular chain in a mixed resin layer. Propylene-ethylene copolymer, propylene-ethylene-butene-1 copolymer, and at least one polypropylene resin selected from low crystalline polypropylene elastomer
2. The composition according to claim 1, wherein the mixing is performed in a range of not more than% by weight.
4. The polyolefin-based stretch packaging film according to Paragraph 3. 5. A dynamic viscoelasticity measurement at a frequency of 10 Hz,
The storage elastic modulus (E ') measured at a temperature of 0 ° C. is 1.0 × 10
¹⁰ dyn / cm ² or less, loss tangent (tan δ) of 0.1
5. The polyolefin stretch packaging film according to claim 1, which is in a range of 0 or more. 6. At least one surface of the mixed resin layer is provided with a melt flow rate (MFR) (JIS K7210, 190
C., 2.16 kg load) is 0.2 to 5 g / 10 min, and the vinyl acetate content is 5 to 25% by weight of the ethylene-vinyl acetate copolymer and / or the α-olefin having 4 to 8 carbon atoms. The polyolefin-based stretch packaging film according to any one of claims 1 to 5, wherein a surface layer containing 5 to 25% by weight of a linear ethylene-α-olefin copolymer as a main component is laminated.